Alfalfa hay is a primary source of feed for dairy and beef feeding operations. While growing, the alfalfa plant is approximately fifty percent leaves and fifty percent stems. Ninety percent of the feeding value, including protein and relative feed value is in the leaf portion of the plant. The feeding value of alfalfa will vary depending on how it is harvested and the resulting ratio of leaves to stems in the harvested alfalfa crop as the leaves will separate from the stems as it is mechanically handled. The common practice of feeders of alfalfa is to pull samples of the harvested alfalfa and send them into a lab to determine the feeding value, so that the ration fed to dairy and beef livestock can be adjusted with other supplements to feed the correct amount of nutrients to produce milk or meat.
One of the main methods for harvesting alfalfa is to use a hay baler, harvesting the alfalfa under sixteen percent moisture content so that the alfalfa does not spoil due to a higher moisture. As the alfalfa dries, it becomes difficult to keep the leaves on the plant as it is baled and the leaves are separated from the stem with the mechanical action of the baler. When baling at sixteen percent moisture, the finished bale will be approximately forty percent leaves and sixty percent stems as the mechanical action of the baler separates some of the leaves. When the hay dries from sixteen down to thirteen percent moisture, additional leaves are separated during baling so the finished bale will be thirty percent leaves and sixty percent stems. This change in the leave to stem ratio leads to a significant reduction in the feeding quality. Multiple tests for the feeding quality are required to identify the different levels of nutrient value between bales due to variation of the moisture at harvest.
Recently, balers have been commonly equipped with a scale device to weigh the bales being made. The leaf portion of the alfalfa plant which is flat will compress to a higher density than the stem portion of the plant which is round. Tests run on alfalfa samples at 16% moisture in a compression chamber with six hundred pounds per square inch of pressure applied, which is similar to the compression applied during baling, illustrate how the properties of compression are influenced by the ratio of leaves and stems as follows:
DENSITY OF SAMPLESBALE VOLUME(POUNDS PER % LEAVES% STEMSBALE WEIGHT(3 FT × 3 FT × 8 FT BALE)CUBIC FOOT)100%0%1440 POUNDS72 CU FT20 pounds80%20%1296 POUNDS72 CU FT18 pounds60%40%1152 POUNDS72 CU FT16 pounds50%50%1080 POUNDS72 CU FT15 pounds40%60%1008 POUNDS72 CU FT14 pounds30%70% 936 POUNDS72 CU FT13 pounds20%80% 864 POUNDS72 CU FT12 pounds10%90% 720 POUNDS72 CU FT10 pounds0%100% 576 POUNDS
Ninety percent of the feeding value of alfalfa is in the leaf portion of the plant. As the leaf to stem ratio changes, the feeding value of the alfalfa also changes as measured by two important values of the feeding quality, protein and relative feed value (RFV). Feeding quality tests run on alfalfa samples at 16% moisture with various leaf to stem ratios show the following values:
TESTED FEED QUALITY% LEAVES% STEMSPROTEINRELATIVE FEED VALUE100%0%28%24080%20%26%22060%40%24%20050%50%23%19040%60%22%18030%70%20%16020%80%16%12010%90%14%1000%100%12%80
Recently, balers have been equipped with moisture sensors. As moisture is added to a bale of hay, the weight of the bale changes, due to the weight of the water within the bale. A test of a bale fourteen inches by sixteen inches by thirty-six inches (4.66 cubic feet) demonstrate the change in weight as water is added to the bale:
% moisture contentbale weight10%46.6 pounds12%47.5 pounds14%48.5 pounds16%49.6 pounds18%50.7 pounds20%51.8 pounds22%53.0 pounds
In the method that has been invented, factoring in the moisture of the bale to the weight of the bale, gives an estimate of the leaf to stem ratio and therefore a method for calculating its feeding value.